1. Field of the Invention
The invention relates firstly to a nail-type fastener, according to the preamble to claim 1, and secondly to a process for manufacturing such fasteners, as according to the preamble to claim 7.
2. Description of the Prior Art
A disadvantage of most known nail-types is that they have a disadvantageous ratio between the amount of material in the nail and the size of the frictional surface of the nail. This is especially true of common round wire nails made of wire with a round cross section. The weight per thousand nails is unfavourably high for the round wire nail. Another disadvantage of this type of nail is that it easily gives rise to severe cracking in the wood.
In order to avoid said disadvantages, several types of nails have been developed with three longitudinal flanges (splines) or with a Y-shaped cross section. Examples of such nails are given in British Patent Specification 10 180 from 1910 and Swedish Patent Specification 127 167. These known designs have not, however, provided a satisfactory solution of the above-mentioned problems, and therefore these nails have not come into wide-spread use.
The purpose of the present invention is to achieve a new type of nail in which the material is utilized more efficiently (than in known nails) to obtain improved strength characteristics, primarily increased flexural rigidity and pull grip. In other words, this new type of nail is to have, with the same nominal size as a conventional, known nail, at least the same flexural rigidity, but using a smaller amount of material in the nail; i.e. the new type of nail is to have a lower weight than the corresponding conventional nail. It must also be possible to produce the nail wire for the new nail more rapidly from a wire of circular cross section than is possible for conventional, rolled nail wires.